Liam made this cool DIY variable speed stir plate for creating yeast starter for his homebrewed beer. To control the speed of the magnetic stirrer, he used an ATmega328 with the Arduino bootloader connected to a PC case fan. Liam even made use of the LEDs that you can sometimes find on fancy fans to give his stir plate nice lighting effects. If you’d like to get started on your own, check out his site for an easy to follow wiring diagram and the code. [Thanks, Natalie!]

Matt Richardson is a San Francisco-based creative technologist and Contributing Editor at MAKE. He’s the co-author of Getting Started with Raspberry Pi and the author of Getting Started with BeagleBone.

Cool project but there are a couple of things worth mentioning. The arduino isn’t really necessary. You can make the same thing with a pot and a few parts for much less cost. (see: http://stirstarters.com/instructions.html) [no affiliation].

Also, you should ditch the airlock and cover loosely with foil. The purpose of the stir plate is to both allow CO2 out, but to get oxygen in. The airlock prevents anything from getting in, including oxygen. On your fermenters, you definitely want to airlock to prevent oxygenation at that stage, but for your starter, you want oxygen getting in.

Whit

Letting oxygen in allows for possible contamination. Yeast needs very little oxygen for homebrew batch sizes. Boil water and sugar to sterilize it, then shake it vigorously to aerate. Throw a fermentation lock on it and wait for it to cool to add yeast. Definitely want to keep the lock on it though.

vladsinger

Used a similar apparatus to spin coat PVA onto glass slides in a materials science lab class at Cornell.

Sparky

Made one with a 12V rated fan but gave it 5V direct from a wall-wart so it did not go too fast. Our kids think having a ‘water tornado’ on the counter is crazy cool.